charging issue - Diesel Forum

Cjhstang · 10-17-2009, 10:16 PM

Well i think i'm down to replacing one of the last remaining components of my truck since i bought it four years ago...

The truck doesn't ever seem to wanna fully charge the batteries from the alternator...

The other day i replaced all gps, put the air filter hat back on touched the metal filter to the hot side of the gp solenoid as the hat seated to the intake, of course that kicked an impressive spark.

started the truck to test gps everything was great. truck sat for two days, temps dropped a little tried to fire her up and would turn over fast at all. batteries are new within two years, starter, terminals, wires, grounds all new.

i've had the batteries hooked up to a trickle charger over night for 12 hr intervals for the last three so i can get to and from work, but it still never fully charges (donno if 12 hours is long enough to charge 2 batteries on a trickel cell tho).

when i do drive when i get higher rpms i do get a higher voltage output. so i am getting something from the alt.

would that spark have fried the alternator?? the truck was off when it happened.
Bad regulator??

How do i test my alternator (at home) and what results would a good alternator yield?

gerryk · 10-17-2009, 10:27 PM

Most parts shops will bench test altenators for free, at least around my neck of the woods they will. Also check the batteries separately. Disconnect both the batteries and check each one by itself. I had one bad battery discharging the other just like you had and if they weren't disconnected the bad battery would test as good.
Once I replaced the batteries I had no more problems for a year and a half then I ran into the same thing you are having. I never figured the problem out as I traded in my 99 on a 2010. Good luck.

Snotzalot · 10-18-2009, 07:54 AM

Charge both batteries, remove the ground from both batteries, check and record the voltage of both batteries, wait 24 hours and retest voltage, if there is a severe drop in one or both batteries you have bad/shorted batteries.

StrokerSmoker7.3 · 10-18-2009, 08:48 AM

If the alternator voltage output is fluctuating with the RPMs sounds like bad diodes in the alternator. I just replaced mine this week because of the same thing. One easy way to tell is, if you sit at a red light or stop sign at night with your headlights on, do they dim when you come to a stop and then get brighter when you give it throttle? If so, the the alternator has one or more bad diodes.

Cjhstang · 10-18-2009, 10:20 AM

Quote:

Originally Posted by StrokerSmoker7.3

If the alternator voltage output is fluctuating with the RPMs sounds like bad diodes in the alternator. I just replaced mine this week because of the same thing. One easy way to tell is, if you sit at a red light or stop sign at night with your headlights on, do they dim when you come to a stop and then get brighter when you give it throttle? If so, the the alternator has one or more bad diodes.

i know it sounds weird but i figured that was normal.. its done that since i bought the truck 4 years ago.

is there a way to test the alternator while its in the truck wo taking it to napa or the like?

Snotzalot · 10-19-2009, 08:39 PM

Inductive amp meter and test the voltage.

Kevin 007 · 10-19-2009, 10:47 PM

How about a bad voltage regulator? Im no expert, just throwing it out there.

StrokerSmoker7.3 · 10-19-2009, 11:08 PM

Yeah go to an Advanced or the like and they should be able to hook it up to an inductive amp meter and test it in the truck. I was also thinking voltage regulator. I want to replace mine and see what happens. It's just the little silver box on the Pass. side fender right? How much do they normally run?

Snotzalot · 10-20-2009, 05:02 AM

What's the voltage at your batteries when the engine is running but all accessories etc off?

StrokerSmoker7.3 · 10-20-2009, 06:07 PM

Quote:

Originally Posted by Snotzalot

What's the voltage at your batteries when the engine is running but all accessories etc off?

Somewhere between 11 and 14 volts I believe

Snotzalot · 10-20-2009, 06:14 PM

It should be a constant 13.8 volts when running.

Cjhstang · 10-20-2009, 10:19 PM

how quickly should it rise to 13.8 after starting the truck? assuming non extreme temperatures.

1987IDI · 10-20-2009, 11:11 PM

Quote:

Originally Posted by Cjhstang

how quickly should it rise to 13.8 after starting the truck? assuming non extreme temperatures.

Even with extreme temps it should read 13 or 14 right away.

CGBear · 10-21-2009, 03:06 AM

Mine's doing the same thing. It sounds like a bad battery. I have one brand new battery and one that just gave up the ghost. The bad battery pulls the new battery down overnight to the point that I have to throw the charger on it in the morning to get it going.

Cjhstang · 10-21-2009, 06:44 PM

well both batteries tested good and so did alternator. donno what the deal is. the voltage at idle a few mins after turning it on is 13.38.

confusing part is after i shut it down and plugged in the trickel cell charger it didn't seem to charge. infact it was showing a very very slow drop in volts over a few mins of holding my gauge to the batteries. started at 12.59 and slowly dropped to 12.54. i'ma let it on all night and through tomorrow. i'll retest it around same time tom eve.

maybe i have a bad wire somewhere that is draining my batteries?

with my results does it sound like my volt regulator is good?